Electric signal device



May l0, 1960 E. F. SMITH 2,936,450

ELECTRIC SIGNAL DEVICE EnedlFeb. zo, 1957 pas ELECTRBC SlGNAL DEVKCE Ernest F. Smith, @alt Park, Mich., assigner to the United States of America as represented by the Secretary of the Army Application February 20, 1957, Serial No. 641,432 8 Claims. (Cl. S40- 388) i (Grantee under :une 3s, Us. code (i952), sec. 265) The invention relates to electric signaling devices, especially to those of the type wherein sound is produced by the rapid vibration of a diaphragm energized by a solenoid and armature.

In the common construction of an electric signaling device, such as a horn, a pulsating solenoid is used to vibrate a diaphragm producing audible frequencies. The solenoid is usually controlled by a pair of electric contacts, one of which is usually responsive to movement of the diaphragm, such that energization of the solenoid will separate the contacts. `As the diaphragm moves under the action of the solenoid, the contacts will be opened, breaking the solenoid circuit, and permitting the diaphragm to return to the original position. As the diaphragm returns, the contacts will be closed, again energizing the solenoid, and repeating the cycle. The above described system does not operate at maximum eiiiciency because the contacts will close before the diaphragm has completely returned to the neutral position, thus, electrical current is expended in changing the direction of the diaphragm displacement, which adds nothing toward increasing the sound produced by the horn but rather is wasted electrical energy.

To increase the efficiency of a horn, it is proposed to synchronize the energizing of the solenoid with the directional movement of the diaphragm such that the force tending to move the diaphragm is in phase with the velocity vector of the diaphragm displacement. This is accomplished by the use of damping means interposed between the diaphragm and the contacts whereby the velocity vector of the diaphragm will be in phase with the diaphragm displacement and contact operation.

It is thus an object of the invention to design an electric signal device wherein the electrical energy is most ethciently expended.

Another object of the invention is to produce an electric signaling device which will provide a long contact life and utilizes a dampener between the vibrating sound producing elements and the contacts.

These and other objects of the invention will become apparent when viewed with regard to the following description and accompanying drawings wherein:

Fig. l is a cross-sectional elevation of an embodiment of the invention including a schematic representation of the electrical circuit.

Fig. 2 is a cross-sectional plan view of the invention taken along the line ll--ll of Fig. l.

Fig. 3 is a graph disclosing the relationship between the armature velocity and displacement and the contact operation.

The invention is illustrated in a general form which may be used with signaling devices utilizing vibrating membranes or diaphragms to produce sound, however, the invention is not limited to this type of signaling device and may be used with other types of signals such as buzzers and clappers.

The elements comprising the signaling device may be lCC enclosed within a housing lll as shown in Fig. l. The actuation of the device is produced by a coil yoke 12 which is supported within housing 10 and is wound with ne wire so as to become an electromagnet upon current liow through the wire. A magnetic armature 14 is supported in proximity to the coil yoke 12 by a leaf spring 16 which is mounted in bracket 17, such that upon energizing of yoke 12 the armature 14 will be attracted thereto.

The sound waves are produced by the diaphragm 18 which is iixedly supported at the edges. A connecting rod 2G links diaphragm 18 to armature 14 thereby imparting the motion of the armature to the diaphragm.

As in the conventional construction, the energization of the coil yoke 12 is controlled by a pair of contact points 22 and 24 which are carried by leaf springs 26 and 28 respectively, which are fixed in insulated spaced relationship on bracket 17. From the circuit shown in Fig. 1, it will be apparent that upon the closing of switch 30 current will flow through contacts 22 and 24 energizing coil yoke 12.

A circular disk 32 is attached to spring 28 and projects away from contact 24 to form a piston of a dash-pot construction interconnecting the contacts with the armature 14. The cylinder element of the dash-pot consists `of circular disk 34 on which the edge has been drawn up to denne a wall 36. Disk 34 is aixed to armature 14 by means of a stud, nut 38 and spacers 40. As will be noted in Fig. l, the center portion of disk 32 is raised to permit clearance for nut 38 and a clearance 42 is provided between disk 32 and wall 36 to regulate the dampening effect between disks 32 and 34.

The operation of the invention is as follows:

In the at rest position of the signal, the distance between springs 26 and 28 is such the contacts 22 and 24 will touch, thereby forming a closed circuit between switch 3i? and coil yoke 12. The spring 16 will position armature 14 away from yoke 12 as shown in Fig. 1.

Upon closing switch 3i) current will ow through coil yoke 12, pulling the armature downward as viewed in Fig. l. Movement of armature 14 is transmitted to both diaphragm 18 and disk 34, thus the disk 34 will be quickly drawn away from disk 32, lowering the air pressure in the void between the disks. The lower air pressure on the underside of disk 32 will permit atmospheric pressure acting on the upper side of disk 32 to push disk 32 downwardly disengaging contacts 22 and 24 and de-energizing coil yoke 12. Once the electric current flowing through yoke 12 terminates, the resilient character of diaphragm 18 and spring 16 will return armature 14 to the position shown in Fig. 1. The resiliency of leaf spring 28 will tend to return contact 24 to engage contact 22, however, the return will be regulated by the dampening edect produced by disks 32 and 34. The contacts 22 and 24 will engage at the proper time, thus completing the cycle which is then repeated at high frequency causing diaphragm 18 to vibrate rapidly producing the desired audio-signal.

The increased efficiency of the invention is due to the relationship between the direction of armature movement and the contact operation. To produce maximum etliciency of this type of signaling device, the motive force applied to the armature must be in phase with the velocity vector of the armature displacement, e.g., the armature 14 should be drawn toward yoke 12 during that portion of the vibration when the armature 14 will be moving toward yoke 12 due to the rebound eiected by the resilient character of spring 16 and diaphragm 18 terminating the upward return movement of armature 14 as viewed in Fig. 1.

In the conventional contact controlled armature-diaphragm signal device the contacts are either connected to the armature directly or through a fast-motion linkage.

which will open the contacts as the armature is drawn toward the coil yoke, however, this construction permits the contacts to close during the time the armature is returning to the original position. Energizing the coil yoke while the armature is still moving away from the yoke will utilize electrical energy to retard the armature movement before the armature will begin the motion back toward the yoke. Since the motion toward the yoke is the work stroke, the eiiiciency of the sig ."i

only on the utilization of electrical energy c. pended during the motion of the armature toward the yoke, While energy expended to retard the motion of the armature is Wasted. It will thus be understood that the energy used to produce sound will be only that energy used to accelerate the armature toward the yoke.

By the use of disk 32 and walled disk 34, a piston-cylinder arrangement is interposed between the armature M and the contacts 22 and Z4, comprising a dash-pot which will provide the desired relationship between contact operation and armature displacement, namely, the coil yoke i2 is energized only when the armature has ceased movement away from the yoke, at which time the coil yoke energization will be in phase with the velocity vector of the armature displacement producing maximum sound for a given amount of electrical energy.

Thus, as the armature 14 vibrates, the movement of disk 34 will act upon disk 32 to vibrate contact 24 into and out of engagement. with contact. 22. 'die spring 2S, contact 24 and disk 32 will therefore constitute a forced vibrating system, while disk 34, armature 14, spring lo and diaphragm i3 comprise the primary vibrating system. By dampening the force applied by the primary vibrating system on the forced vibrating system a change in the phase relation of the displacements of the systems, but not the period of vibration, will be effected.

Fig. 3 discloses the relationship between armature velocity achieved with the construction of the invention.

VFrom observing the point the various curves cross the X axis, it will be noted that the contact operation lags the armature displacement by approximately 90 and that the contacts will be closed applying a force to the armature in phase with the velocity vector of the armature displacement, which isV approximately between l803 60 of the cycle as illustrated.. From the graph it will also be apparent that the contacts remain open and closed for equal portions of the cycle. With the conventional contact linkage the contacts are open about one-fourth of thev cycle and closed the remaining three-fourths which means that the contacts would be closed during portions of the cycle when the armature velocity vector and displacement would be out of phase. The amount of damping produced by disks 32 and may be determined by the amount of clearance provided at 42 as the clearance 42 will determine the rate at which air will flow to and from the void between the disks.

Thus, by proper phasing of the contact operation in relation to the armature displacement and velocity vector the eiciency of a signaling device may be improved such that a given amount of electrical current will produce an audio-signal of greater intensity.

I claim:

l. In an electric signal device, a vibratable sound producing member, energizable primary vibration means connected to said sound producing member for actuating vibration thereof, control means actuatable by said primary vibration means for controlling energization thereof, and movable phase regulating means carried by said primary means and said control means, said regulating means -being movably actuatable by said primary means for regulating actuation of said control means.

2. An electric signal device comprising, in combination, a vibratable sound producing member, energizable primary vibration means connected to said sound producing member for'actuating vibration thereof, resiliently mounted circuit breaker means in circuit with and actuatable by said primary means for controlling energiza tion thereof, and movable dampening means interconnecting and carried by said primary means and said circuit breaker means, said dampening means being movably actuatable by said primary means for regulating actuation of said circuit breaker means.

3. An electric signal device comprising, in combination, a vibratable sound producing member, electromagnetic means connected to said sound producing member for actuating vibration thereof, circuit interrupting means in circuit with and actuatable by said electromagnetic means for controlling energization thereof, and movable dampening means interconnecting and carried by said circuit interrupting means and said electromagnetic means, said dampening means being movably actuatable by said electromagnetic means for regulating actuation of said circuit interrupting means.

4. An electric signal device comprising, in combination, a vibratable sound producing member, an electromagnetic element linked to said sound producing element for actuating Vibration thereof, a pair of contacts for controlling ow of electricity to said electromagnetic element, and a movable vibration dampener interconnecting and carried by said electromagnetic element and one of said contacts, said vibration dampener being movably actuatable by said electromagnetic element for regulating contact between said contacts.

5. Anl electric signal device comprising, in combination, a vibratable sound producing element, an'armature linked to said sound producing element for actuating vibration thereof, an electromagnet positioned for actuating movement of said armature, electric contacts in circuit with said electromagnet for controlling flow of electricity therethrough, and movable dampening means interconnecting and carried by said armature with said contacts, said dampening means being movably actuatable by said armature for regulating actuation of said contacts.

6. An electric signal device comprising, in combina-l said iirst dampener element for regulating actuation of said circuit'interrupter whereby operation of said circuit interrupter is induced by movement of said armature causing vibration of said sound producing member.

7. An electric signal device comprising, in combination, a vibratable sound producing member, a spring supported armature, means for connecting said armature to said sound producing member, an electromagnet adapted to actuate movement of said armature, means for energizing said electromagnet, a pair of normally engaging spring supported electrical contacts in circuit with said electromagnet for controlling energization thereof, a movable cylindrical element xed to said arma ture adapted to receive therein a movable piston element carried byV one of said contacts and being movably coactable with said cylindrical element for regulating actuation of said contacts whereby movement of said armature will cause said contacts to disengage and engage Vibrating said sound producing member.

8. 'An electric signal device comprising, in combination, a vibratable diaphragm, a spring supported vmovable armature, means for connecting said armature to said diaphragm, an electromagnet adapted to actuate movement of said armature, means for energizing said electromagnet, a pair of normally engaging spring supported contacts in circuit with said electromagnet for controlling energization thereof, a movable cylindrical element carried by said armature and Aa movable piston element carried by one of said contacts positioned in and movably 5 with said cylindrical element for regulating actuation of said contacts whereby movement of said arma-ture will make and break the electromagnet circuit causing said diaphragm to vibrate.

References Cited in the le of this patent UNITED STATES PATENTS 793,063 Ghegan ....V- '.lune 27, 1905 1,898,394 Riedel Feb. 21, 1933 2,048,984 Zenninger July 28, 1936 

